what i've found that was usable:
12" crescent wrench
pliars
zip ties
20$-30 in cash
endless cellphones (always around the corner from gas stations)
wallets
keys
bungie-cords
belts (wtf ?)
ear rings
a watch
socks
a cb radio
some kind of RF tester thing
on the rare really good day, 1/2 a joint

I found a cash register/POS terminal in the ditch at a small pull-off on a highway a fair distance from any towns. The terminal was smashed and there were no identifying marks or cash. I salvaged the barcode reader and pin pad/card reader but have yet to find a use for them.

I found an army shovel on a trail, one of the good old wood handled ones.
Keep it under the seat of my truck for emergency's.

A group of us stopped for a break along Dr. Park trail in Taylor Park. One of my buddies says, "Lookee here!" A little pot pipe was sitting right on a tree branch. We called it "dope pipe trail" from then on.

I face planted, hard, on a trail in the Cove, in Virginia, sitting right in front of my face was a pair of really cool and expensive looking sunglasses. They where in perfect shape, I wore them the rest of the day, handy since my googles kept fogging up. I then left them in the pocket of my riding pants when I put them in the washer, and broke them.....

I found an Echo gas powered weed eater. It was fairly damaged from hitting the road, and would only do half throttle, which was more than enough for my little yard. I used it for about 5 years before it wore out.

Friend was telling me last night how about 25 years ago, he saw a big metal toolbox sliding down a street in New Orleans in a shower of sparks. No vehicles in sight so a complete mystery where it had come from. Guessed that someone had it in a pickup and hit a bump then turned off while the toolbox carried on for a couple of blocks by itself. Contained a complete set of SAE tools (wrenches, sockets, etc.) so nothing terribly useful unless you're working on an old tractor

I don't remember finding anything terribly exciting while riding (a couple of screwdrivers maybe) although I did pick up a box of high explosive shaped charges one time when in my car.

I found an Echo gas powered weed eater. It was fairly damaged from hitting the road, and would only do half throttle, which was more than enough for my little yard. I used it for about 5 years before it wore out.

Two stroke? I worked for a landscaping company and we had a bunch of those... They were great, but they would gum up real quick if you didn't keep them WFO all the time.